Field of the Invention and Related Art Statement
The present invention relates to an apparatus for decoding BCH (Bose-Chaudhuri-Hocquenghem) code capable of correcting double errors, by use of a Chien search method.
As one of the methods of decoding the BCH code which can correct double errors, there has been known a decoding method whereby two syndromes S1 and S3 are formed from the receiving sequence and then the error-location polynomial EQU .sigma.(x)=x.sup.2 +S1 x+S1.sup.2 +(S3/S1)
is solved by the method called the Chien search method, thereby correcting the errors in the receiving sequence.
In this decoding process, the calculation of the syndromes S1 and S3 and the calculation of S1.sup.2 can be relatively easily realized due to a hard-wired logic arrangement such as a gate array or the like. However, the dividing process of S3/S1 needs complicated calculations. Therefore, the method is performed using a dividing process performed using a ROM which limits the speed of operation which can be obtained.
When the decoding apparatus is in the form of an LSI, with the dividing circuit constituted by a PLA, the scale of the LSI chip is enlarged, which is a drawback. On the other hand, when dividing circuit is constituted by a ROM, the decoding processing time is restricted due to the access time, resulting in the drawback that the decoding process cannot be executed at a high speed.